Fecal Microbiota of Cats With Naturally Occurring Chronic Diarrhea

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    F e c a l M i c r o b i o t a o f Ca t s w i t h N a t u r a l l y O c c u r r i n g Ch r o n i cD i a r r h e a As s e s s e d U s i n g 1 6 S r RN A G e n e 4 5 4 - P y r o se q u e n c i n g

    b e f o r e a n d a f t e r D i e t a r y T r e a t m e n t

    Z. Ramadan, H. Xu, D. Laflamme, G. Czarnecki-Maulden, Q.J. Li, J. Labuda, and B. Bourqui

    Background: The gastrointestinal (GI) microbiota has a strong impact on the health of cats and these populations can bealtered in GI disease. Little research has been done to associate improvement in diarrhea with changes in GI microbiota.

    Objective: To evaluate GI microbiota changes associated with diet change and related improvement in diarrhea in cats

    with chronic naturally occurring diarrhea.

    Animals: Fifteen adult Domestic Shorthair cats with naturally occurring chronic diarrhea.

    Methods: Controlled crossover dietary trial for management of diarrhea. Fecal microbiome was assessed using 454-py-

    rosequencing. Relationships among fecal score (FS), diet, and microbiome were explored using partial least square method,

    partial least square method discriminant analysis, and orthogonal partial least square method with discriminant analysis

    (OPLS-DA).

    Results: Dominant bacterial phyla included the Firmicutes and Bacteroidetes, followed by Fusobacteria, Proteobacte-

    ria, Tenericutes, and Actinobacteria. Orthogonal partial least squares (OPLS-DA) clustering showed significant microbial

    differences within cats when fed Diet X versus Diet Y, and with Diet Y versus baseline. Significant correlations were found

    between the microbiome and FSs. Those bacteria with the strongest correlation with FS included Coriobacteriaceae Slac-

    kia spp., Campylobacter upsaliensis, Enterobacteriaceae Raoultella spp., Coriobacteriaceae Collinsella spp., and bacteria of

    unidentified genera within the families of Clostridiales Lachnospiracea and Aeromonadales Succinivibrionacease, suggest-

    ing that increased numbers of these organisms may be important to gut health.Conclusions and Clinical Importance: Alterations in intestinal microbiota were associated with improvement in diarrhea,

    but, from our data we cannot conclude if changes in the microbiome caused the improvement in diarrhea, or vice versa.

    Key words: Gastroenterology; Nutrition.

    The gastrointestinal (GI) microbiota has a strongimpact on the health of cats and dogs,1 and themicrobiome can be altered in GI disease.24 Priorresearch has confirmed alterations in intestinal micro-biota in cats with GI disease.5,6 Documented changes

    include increases in Clostridium spp., and decreases in

    Bidifobacteriumspp., Lactobacillusspp. andBacteriodes

    spp.,68

    all of which may be influenced by dietary char-acteristics including fermentable fiber.3,913 Studies have

    shown that dietary changes can result in clinicalimprovement in diarrhea in cats and dogs.1420 In other-

    wise healthy dogs, dietary-induced changes were associ-ated with altered microbiota, altered fecal quality, or

    both.21,22 However, comprehensive studies are lackingto determine if clinical improvement in cats with diar-

    rhea is associated with changes in the GI microbiome.Metagenomics is the analysis of genomic patterns of

    entire communities of microbes, such as the intestinal

    microbiome. The ability to perform such analyses using

    454-pyrosequencing, which allows accurate and quanti-tative analysis of DNA, provides a more comprehensive

    view of the microbiome without the limitations of cul-ture methods.23,24 Although there is evidence that the

    intestinal microbiota differs along the GI tract, fecalsamples are more readily available for clinical studies,

    and alterations in fecal microflora have been shown tooccur in cats with diarrhea.6,25,26 In this study, 16SrRNA sequence data were analyzed using 454-pyro-

    sequencing to characterize the fecal microbiome in cats

    with chronic diarrhea before and after response to die-tary treatment. Our objectives were to characterize thephylogeny of the feline fecal microbiome, assess the

    changes induced by the therapeutic diets, and to corre-late these microbial community changes with clinical

    improvement in diarrhea assessed by fecal scores (FS).

    Materials and Methods

    Animals

    Freshly voided fecal samples were collected from adult

    Domestic Shorthair cats undergoing a controlled, crossover

    From the Nestle Research Center, St. Louis, MO (Ramadan,Laflamme, Czarnecki-Maulden, Li, Labuda); the Nestle Purina

    Product Technology Center, St. Louis, MO (Xu); and the Nestle

    Product Technology Center, Konolfingen, Switzerland (Bourqui).

    This research was conducted at the NestlePurina Pet Care Center

    in Missouri and the Nestle Research Center in St. Louis, MO

    between 2008 and 2009. This study was presented in abstract form

    at the 2013 ACVIM Forum, Seattle, WA.

    Corresponding author: Dr Ziad Ramadan, Nestle Research

    Center, Checkerboard Square 2S, St. Louis, MO 63164; e-mail:

    [email protected].

    Submitted August 16, 2013; Revised October 8, 2013;

    Accepted October 24, 2013.Copyright 2013 by the American College of Veterinary Internal

    Medicine

    10.1111/jvim.12261

    Abbreviations:

    FS fecal score

    GI gastrointestinal

    OPLS-DA orthogonal partial least square method with

    discriminant analysis

    OTU operational taxonomic unit

    PCA principal components analysisPLS-DA partial least square method discriminant analysis

    PLS partial least squar e method

    J Vet Intern Med2014;28:5965

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    clinical trial for the dietary management of chronic diarrhea. The

    clinical design and other aspects of this study have been previ-

    ously reported.20 Briefly, cats with naturally occurring diarrhea

    lasting at least 3 months were identified among cats at the Nestle

    Purina Pet Care Center in Missouri, USA. Diarrhea was defined

    as a FS of 6 or 7 using a 7-point scoring system where

    1 = extremely dry and firm, 23 = normal stools, and 7 = very

    watery.20 Cats were excluded from the study if they had received

    any treatment for diarrhea in the 6 weeks before initiation of the

    study or if they had evidence of intestinal parasites, infectious

    disease, or a systemic disease that may cause diarrhea.

    Study Design

    The study protocol was approved by the Nestle Purina Institu-

    tional Animal Care and Use Committee. Sixteen cats were

    selected and were individually housed. Once cats were assigned

    to housing, the units were arbitrarily divided into 2 equal-sized

    groups. In order to minimize effects caused by differences in the

    cats previous diets and to adapt all cats to a canned food diet,

    all cats entered into the study were fed the same canned mainte-

    nance dieta during a 2-week baseline period (Baseline). This per-

    iod was considered sufficient because prior studies documentedthat if cats with diarrhea respond to dietary change, they usually

    do so within 12 weeks.15,16,19 Two cats refused to eat the canned

    diet and were replaced during the baseline period. One group of

    cats then was fed Diet Xb whereas the other group was fed Diet

    Yc as their sole diet for 1 month (Period 1), after which they

    were switched to the alternate diet for an additional month (Per-

    iod 2). Cats were individually fed once daily based on daily

    energy requirements and water was available ad libitum. Data

    collection occurred during the last week on each diet. FSs were

    assigned daily by 1 of 3 technicians trained in fecal scoring, with

    each feces being scored separately. During each of the last 3 days

    of each period, freshly voided fecal samples were collected, mixed

    with 10% w/w glycerol, flushed with CO2, and frozen at 80C

    until analysis. Collection and processing of fecal samples were

    performed within 15 min of defecation.

    Extraction of DNA and Metagenomic454-Pyrosequencing

    Genomic DNA was extracted from fecal samples using the

    method of Tsai and Olson.27 Briefly, fecal samples were thawed

    in ice, weighed and suspended in phosphate-buffered saline

    (0.85% NaCl, 120 mM NaH2PO4, pH = 8.0) then centrifuged at

    5525 9 g for 10 min. After discarding the supernatant, the pellets

    were resuspended in 0.5 mL lysis solution (0.15 M NaCl, 0.1 M

    EDTA, pH = 8.0) containing 15 mg/mL lysozyme and incubated

    for 30 min with constant agitation in a 37C shaking water bath

    before, and another 30 min after, addition of 0.5 mL of sodium

    Tris sodium-dedocyl-sulfate solution (0.1 M NaCl, 0.48 M TrisHCl [pH = 8.0], 10% sodium-dedocyl-sulfate, pH = 8.0). Three

    freeze-thaw cycles were performed to break open the bacterial

    cell walls. After the third thaw, Proteinase Kd was added to each

    sample to a final concentration of 50 lg/mL and samples were

    again incubated in a 37C shaking water bath for 30 min with

    constant agitation, then centrifuged at 17,500 9 g for 20 min in

    a refrigerated microcentrifuge. Without disturbing the pellet,

    850 lL of the supernatant was removed and placed into a clean

    tube on ice. Samples remained on ice for the remainder of the

    processing. Samples were mixed with an equal volume of phenol

    (pH = 7.9), then centrifuged for 6 min at 16,500 9 g . An equal

    volume of phenol/chloroform/isoamyl alcohol (25 : 24 : 1) was

    mixed with 700 lL supernatant, then again centrifuged for 6 min

    at 16,500 9 g. This supernatant (550 lL) was mixed with an

    equal volume of chloroform/isoamyl alcohol (24 : 1) then centri-

    fuged at 16,500 9 g for 6 min. A 400 lL aliquot of this superna-

    tant was mixed with 400 lL ice cold isopropanol and 96 lL

    10.5 M ammonium acetate (1.125 M final concentration), then

    frozen at 80C freezer overnight or until processing (up to

    2 weeks).

    Samples were thawed on ice for ~510 min before further pro-

    cessing. DNA pellets were obtained by centrifuging at

    17,500 9 g for 20 min in a refrigerated microcentrifuge. The

    supernatant was removed and pellets were washed with 500 lL

    70% ethanol, then dried. The pellets were resuspended in 200 lL

    Tris-EDTA buffer (10 mM Tris HCl [pH = 8.0], 1 mM EDTA,

    pH = 8.0). DNA was quantified by Quant-It.e All samples were

    then stored at 80C until further analysis.

    Metagenomic 16S rRNA pyrosequencing was performed by

    Core for Applied Genomics and Ecology.f The V1V2 region of

    the 16S rRNA gene was amplified using bar-coded fusion primers

    with the Roche-454 A or B titanium sequencing adapters, fol-

    lowed by a unique 8-base barcode sequence (B) and finally the 5

    ends of primer A-8FM (5-CCATCTCATCCCTGCGTGTC

    TCCGACTCAGBBBBBBBBAGAGTTTGATCMTGGCTCAG)

    or primer B-357R (5-CCTATCCCCTGTGTGCCTTGGCAGT

    CTCAGBBBBBBBBCTGCTGCCTYCCGTA-3). All PCR reac-tions were quality controlled for amplicon saturation by gel elec-

    trophoresis; band intensity was quantified against standards

    using GeneToolsg image analysis software. For each region of a

    2-region picotiter plate, amplicons from 48 reactions were pooled

    in equal amounts and gel purified. The resulting products were

    quantified using PicoGreenh and a Qubit fluorometeri before

    sequencing using a Roche-454 GS-FLX Pyrosequencer.j

    Data Processing Pipeline

    The raw data from 454-pyrosequencing were processed using

    QIIME.28 Data were filtered to remove low-quality reads not

    meeting the following quality criteria: (1) a complete barcode

    sequence immediately followed by a forward primer sequence,

    with no mismatch in either barcode or primer sequence; (2) read

    lengths between 200 and 1,000 bases; (3) average quality score of

    25 or higher in a sliding window of 50 bases; and (4) maximum

    homopolymer run of 6. Processed reads were then demultiplexed

    into barcode-indexed sample categories. The barcode, forward

    primer, and reverse primer were subsequently trimmed from each

    read. This yielded a total of 556,366 reads from 48 samples with

    an average of 11,591 reads per sample. The average length for

    the reads was 358 bases.

    Reads were clustered into operational taxonomic units (OTU)

    using a reference-based UCLUST algorithm at a 97% sequence

    similarity level.29 The reference data file was obtained from the

    greengenes website (\http://greengenes.lbl.gov, 2011 release).

    A consensus taxonomic lineage was assigned to each OTU using

    the ribosomal database project (RDP) nave Bayesian classifier

    30

    at a minimum confidence interval of 0.8. The RDP classifier was

    retrained using the greengenes taxonomy. Finally, an OTU table

    was constructed with proper taxonomic identifications for each

    OTU.

    Statistical Data Analysis

    Mean fecal scores (FSm) for each cat were determined by aver-

    aging all of that cats scores recorded during the last 7 days of

    each study period. FSs were not affected by feeding order

    (period), so data from both periods were pooled. The relation-

    ships between FSm, diet and microbiome were explored using

    partial least square method (PLS), partial least square method

    discriminant analysis (PLS-DA), and orthogonal partial least

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    square method with discriminant analysis (OPLS-DA) using

    SIMCA-P+k and MATLABl routines. PLS is a chemometrics

    method used to measure quantitative relationships between 2

    data sets where both are matrices, usually comprising spectral

    data such as calibration samples (X), and a set of quantitative

    values (Y). For PLS-DA, the Y matrix contains qualitative val-

    ues (eg, presence of diarrhea or treatment group). OPLS-DA is a

    multivariate method used to eliminate extraneous variance from

    the X data matrix that is unrelated to class, in this case, FSs.

    Having removed the extraneous variation (eg, intersubject age,

    sex), the OPLS-DA models enhance the predictive ability of the

    model and simplify interpretation.31,32 A standard 7-fold cross-

    validation method was applied to establish the robustness of the

    models. In OPLS models, R2X, R2Y , a nd Q2 are reported.

    The values of R2X and R2Y show how much of the variation in

    the datasets X and Y, respectively, are explained by the model.

    The cross-validation parameter, Q2 (which can range from 1 to

    +1), represents the predictability of the models and is used to test

    the validity of the model against overfitting. A positive Q2 value

    indicates that differences between groups are statistically signi-

    ficant, whereas a negative Q2 value indicates no significant

    relationship among the data.

    Principal components analysis (PCA) and pairwise discrimi-nant analysis were applied to sample classes (diets) with unit vari-

    ance scaling (each parameter has a mean of 0 and a variance of

    1). This approach filters out metagenomic information that is not

    correlated with the predefined classes whereas the loadings yield

    information on which bacterial signals are associated with the

    observed clustering, thus giving a means for metagenomics inter-

    pretation. Pairwise OPLS-DA models were generated with 1 pre-

    dictive component, and 2 orthogonal components to discriminate

    among the 3 diets. Models were calculated using family, genus,

    and species levels. OPLS-DA plots were generated only to species

    level.

    Results

    One cat was withdrawn from the study for unrelatedmedical reasons. Fifteen cats (13 neutered males,

    2 spayed females; mean age, 10 years [range,617 years]) completed all phases of the study, as pre-

    viously described.20 Most cats had signs consistentwith either large bowel (n = 7) or mixed large andsmall bowel (n = 7) diarrhea. Mean FS improved

    (P < .01) from baseline (5.5 0.3) after both Diet X

    (5.0 0.4 and 4.4 0.4 for periods 1 and 2, respec-tively) and Diet Y (4.0 0.6 and 4.2 0.5 for periods

    1 and 2, respectively), with significantly greaterimprovement after Diet Y (P < .01). Changes in FS inresponse to diet were not affected by the order in

    which the diets were fed (P = .65). Individual FSimproved at least 1 unit in 40% of the cats while fedDiet X, and in 67% of the cats while fed Diet Y,resulting in normal stools (FS 3) in 13.3% of cats

    fed Diet X and in 46.7% of cats fed Diet Y. 20

    Pyrosequencing of fecal samples detected 8 phyla, 14

    classes, 25 orders, 47 families, 96 genera, and 146species of bacteria. Firmicutes, Bacteroidetes, Fusobac-

    teria, Proteobacteria, Tenericutes, and Actinobacteriawere the most abundant phyla in these cats (Table 1).

    The most prevalent bacterial classes were Bacilli andClostridia among the Firmicutes and Bacteroidia and

    Flavobacteria among the Bacteroidetes. Prevotella was

    the most abundant genus in fecal samples regardless of

    diet consumed, with mean of 24% across all samples,followed by Fusobacterium (9%), unclassified Fusobac-teriaceae (9%), Clostridium (8%), and Streptococcus

    (6%).The OPLS-DA models showed significant differencesin the fecal microbiome of cats when fed Diet Y versus

    baseline at the family (Q2 = 0.126), genus (Q2 = 0.399),and species (Q2 = 0.61, Fig 1A) level. Likewise, signifi-cant but smaller differences were noted between cats

    fed Diet X versus Diet Y at the family (Q2 = 0.0588),genus (Q2 = 0.127), and species (Q2 = 0.197, Fig 1B)

    levels. There were no differences after Diet X com-

    pared to baseline. OPLS-DA clustering showed thegreatest microbial differences in cats when fed Diet Yversus baseline (Q2 = 0.61).

    Significant changes in bacterial populations occurredin cats fed diet Y versus baseline or diet X (Fig 2).

    For example, the species Clostridium perfringens,Prevotella copri, Plesiomonas shigelloides, Helicobacter

    cinaedi, Lactobacillus helveticus, and Bacteroides fragi-lis and others were decreased and Ruminococcus gna-

    vus, Streptococcus suis and Eubacterium dolichum wereincreased in cats fed diet Y compared to baseline.

    Other unidentified species in various genera also chan-ged in cats fed diet Y. Some of these alterations also

    were found with diet X but not to the same extent,consistent with the observation that Diet X was inter-mediate to Diet Y regarding improvement in FS.

    Using OPLS-based evaluations, significant correla-

    tions between microbiome and FS were found for cats

    fed Diet Y at the genus (Q2 = 0.464) and species(Q2 = 0.115) levels, as well as for cats fed Diet X at

    family (Q2 = 0.232), genus (Q2 = 0.736), and species(Q2 = 0.717) levels. Prediction plots generated from

    the OPLS data at the species level, wherein FSs were

    predicted based on the microbiome, showed strongcorrelations between predicted and actual FS (r2 = 1.0and 0.6, P < .005, for Diets X and Diet Y, respec-

    tively). OPLS regression identified 63 different bacteriawith significant negative or positive correlations

    (r > 0.2; P .05) to FS in cats consuming Diets Xor Y, although they differed between diets (Table S1:

    on-line supplement) Those organisms most strongly

    correlated (r > 0.70) with FS were within cats while

    Table 1. The phylum level composition of the fecalmicrobiota in cats with chronic diarrhea fed different

    diets. This analysis was computed using both V1V2regions.

    PhylumTotal Baseline Diet X Diet Y

    Percent of bacteria

    Firmicutes 34.34 33.72 35.65 33.82

    Bacteroidetes 30.05 33.54 30.16 26.13

    Fusobacteria 18.81 14.66 16.57 25.43

    Proteobacteria 7.66 9.14 7.52 6.16

    Tenericutes 6.56 6.21 7.45 6.12

    Actinobacteria 2.57 2.72 2.65 2.33

    Cyanobacteria 0.0034 0.0036 0.006 0.0008

    TM7 0.0003 0.0007 0 0

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    fed Diet Y, and included Coriobacteriaceae Slackiaspp. (r = 0.83), Campylobacter upsaliensis (r =0.79), Enterobacteriaceae Raoultella spp. (r = 0.72),and bacteria of unidentified genera within the familiesof Clostridiales Lachnospiracea (r = 0.76), and Aero-

    monadales Succinivibrionacease (r = 0.71).

    Discussion

    To our knowledge, this study is one of the first to

    apply next generation pyrosequencing to character-ize the hindgut microbiome of cats with chronic diar-

    rhea, and to show changes in the microbiome withimprovement in diarrhea associated with dietary man-

    agement. The data showed strong correlations betweenFS after consumption of therapeutic diets and several

    organisms, generating a model that accurately pre-dicted the FS of these cats based on the microbiota.

    Those bacteria with the strongest correlation with

    FS-included Coriobacteriaceae Slackia spp., Campylo-bacter upsaliensis, Enterobacteriaceae Raoultella spp.,Coriobacteriaceae Collinsella spp., and bacteria of

    unidentified genera within the families of ClostridialesLachnospiracea and Aeromonadales Succinivibriona-

    cease, suggesting that increased numbers of theseorganisms may be important to gut health.

    In this study, we detected the presence of 8 bacterialphyla. Dominant bacterial phyla included the Firmi-

    cutes and Bacteroidetes, both of which comprised 3034% of all sequences. Firmicutes includes, among

    many others, the commonly recognized genera Lacto-bacillus, Clostridium, and Enterococcus, whereasBacteroidetes includes Helicobacteria, Escherichia,

    Pasturella, and Pseudomonas among its genera. These

    were followed in abundance by Fusobacteria (18.8%),Proteobacteria (7.7%), Tenericutes (6.6%), and

    Actinobacteria (2.6%). The proportions were similaracross all diets with the exception that Fusobacteriawere higher in cats fed Diet Y. Although the specific

    abundance of Firmicutes in this study is less, and theabundance of Bacteroidetes and Tenericutes is morethan reported by others, our results are consistent with

    most other studies using nonculture methods of evalu-ation, indicating that the dominant phyla in cat fecesare Firmicutes, Bacteriodetes, Proteobacteria, Fuso-

    bacteria, and Actinobacteria.2426,33,34 In contrast, Tunet al. reported that Bacteroidetes were the most preva-

    lent in cats (68%), followed by Firmicutes (13%) andProteobacteria (6%).35 The reported differences in spe-

    cific abundance among these phyla may be related todifferences in diets consumed, or differences in meth-

    ods and the use of bacterial primers that target certainhypervariable regions of the 16S rRNA. The selection

    of bacterial primers of the 16S rRNA is an importantfactor in any metagenomics study because some prim-

    ers could underestimate or overestimate certain classesof bacteria.24,26,36 The large number of Tenericutes rel-

    ative to prior papers may be related to recent changesin taxonomy, with many genera in the Tenericutes

    phylum previously classified as Firmicutes.37,38 How-ever, the differences between results from this studyand prior studies may reflect true differences in bacte-

    rial populations associated with naturally occurringchronic diarrhea.

    The microbiota of cats at baseline with active diar-

    rhea and of cats after being fed Diet X with partial res-

    olution of diarrhea were very similar. However,samples collected after Diet Y, which was associated

    with greater improvement in diarrhea, showed signifi-cant differences compared to baseline and compared to

    Diet X. Mostly, these changes were in the same direc-tion; ie, the abundance was increased or decreased

    compared to both baseline and Diet X. Among the fewexceptions, Eubacterium spp., Enterococcus spp. and

    Streptococcus suis all were increased after Diet Y com-pared to baseline but decreased compared to Diet X.

    Many of the organisms frequently identified usingculture methods, such as Lactobacillus spp., Bifidobac-

    terum, C. perfringens, and Escherichia coli, showed

    weak or no correlation with fecal quality in this study.

    A

    B

    Fig 1. Orthogonal partial least square with discriminant analysis

    (OPLS-DA) plot, showing results of multivariate analysis of the

    effects of dietary changes on fecal microbiota at the species level.

    Data were visualized by means of component scores plots, where

    each point represents an individual metagenomic profile of a

    sample. The score matrix (tcv and to) represent projections onto

    the latent variables of the OPLS-DA model. (A) Scores plot

    showing significant differences (P < .01) between Diet Y versus

    Baseline; and (B) Scores plot showing significant differences

    (P < .01) between Diet Y versus Diet X.

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    C. perfringens, however, was significantly decreased incats fed Diet Y compared to baseline and compared to

    Diet X. Previous work had shown a positive correla-

    tion between increased dietary protein and Clostridium,including C. perfringens.13,39 In this study, Diet Y con-tained more protein than Diet X, so factors other than

    dietary protein also affect fecal C. perfringens. SomeLactobacillus species, such as L. helveticus, also were

    increased in cats fed Diet Y. Desulfovibrio spp., anorganism previously shown to be increased in cats with

    inflammatory bowel disease,6 also was increased in catsfed Diet Y compared to baseline and Diet X.

    However, there was no correlation between this organ-ism and FS in the cats in this study.

    There were some limitations to this study. It was a

    clinical study evaluating cats with chronic, naturallyoccurring diarrhea, and only 15 cats were available forthe study. The use of a crossover design increased the

    power of the study and helped overcome the inherentvariation in individual differences in microbiota. Cats

    were given 3 weeks to adapt to each diet before begin-ning the sampling period, which previously has been

    documented as sufficient for a stable response to die-tary change in cats with diarrhea,15,16,19 but there was

    Fig 2. Heat map plot of significant bacterial microbiota. The heat plot (r range from1 to +1) indicates the abundance of bacteria that

    were up- or down-regulated in cats after eating each diet. Red corresponds to bacteria that are up-regulated in Diet Y (high positive r

    correlation value) and green corresponds to bacteria that are down-regulated in Diet Y (high negative r correlation value) which resulted

    from the OPLS-DA model. The bacterial genera and species were grouped according to their phylum level.

    Microbiota in Feline Diarrhea 63

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    not a washout or return to baseline between dietarytreatments. When planning the study, it was assumedthat there would be no carryover effect because cats

    with diet-responsive diarrhea usually respond within12 weeks and a 3-week adaptation time during each

    phase was allowed before initiating sample collec-tions.16,20 The lack of washout did not appear to

    impact the results because the order in which the dietswere fed did not have a significant effect on the results.

    Cats had poor FS at the beginning of the study whichimproved after consuming the therapeutic diets, but

    based on the study design it is not possible to differen-tiate the effects of diet on the microbiome from theeffects of improvement in diarrhea.

    Conclusions

    In this study, we quantified variations in the compo-sition of hindgut microbiota in cats with chronic diar-

    rhea and after clinical improvement while being fed 2

    therapeutic diets. The bacterial phyla Firmicutes andBacteroidetes each comprised 3034% of all sequencesin this study, which is less for Firmicutes and more for

    Bacteroidetes compared to most other studies. It is notknown if the differences are because of methodology

    or because of health or dietary effects. Those bacteriawith the strongest correlation with FS included Corio-

    bacteriaceae Slackia spp., Campylobacter upsaliensis,Enterobacteriaceae Raoultella spp., Coriobacteriaceae

    Collinsella spp., and bacteria of unidentified generawithin the families of Clostridiales Lachnospiracea and

    Aeromonadales Succinivibrionacease, suggesting thatincreased numbers of these organisms may be impor-

    tant to gut health. Finally, from our data we cannot

    conclude if these changes in the microbiome causedthe improvement in diarrhea or were a result of either

    the diet or the improved fecal quality.

    Footnotes

    a Baseline maintenance diet: Fancy Feast Savory Salmon Feast

    Cat food, Nestle Purina PetCare Company, St. Louis, MOb Diet X: Hills Prescription Diet i/d Feline, Hills Pet Nutri-

    tion Inc, Topeka, KSc Diet Y: Purina Veterinary Diets EN Gastroenteric brand

    Feline Formula, Nestle Purina PetCare Companyd Proteinase K: Fisher BioReagents # BP1700-500, Fisher Scien-

    tific, Pittsburg, PAe Quant-It: Invitrogen Quant-It kit, dsDNA, broad range, Life

    Technologies, Grand Island, NYf Core for Applied Genomics and Ecology, University of

    Nebraska-Lincoln, Lincoln, NEg GeneTools image analysis software, Syngene, Frederick, MDh PicoGreen: Invitrogen, Life Technologiesi Qubit fluorometerg: Invitrogen, Life Technologiesj Roche-454 GS-FLX Pyrosequencer: 454 Life Sciences, a Roche

    company, Branford, CTk SIMCA-P+, verion 12.0.1.0: Umetrics AB, Umea, Swedenl MATLAB: MathWorks Inc, Natick, MA

    Acknowledgments

    The authors thank the staff veterinarians and techni-cians at the Nestle Purina Petcare Center for assistance

    with data collection and animal care. This study wassupported by the Nestle Research Center St. Louis.

    Conflict of Interest: This project was funded and

    conducted by Nestle Purina PetCare, St. Louis, MO

    63164. All authors are full-time employees of this com-pany.

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    Supporting Information

    Additional Supporting Information may be found inthe online version of this article:

    Table S1. Fecal microbiota, determined by 454pyrosequencing that were significantly (P < 0.05) cor-

    related with fecal scoresa from cats with naturallyoccurring chronic diarrhea after being fed therapeutic

    diet Diet Xb or Diet Yc for 4 weeks. Bacteria are

    sorted according to their phylum.

    Microbiota in Feline Diarrhea 65